Gearboxes for wind turbines are required to operate near-continuously for extended periods of time, at very high loads and in challenging environmental conditions, ideally with minimal downtime for service or repair. Periodic inspection or service is nonetheless required, in order to check for signs of wear or other damage. The bearings within such gearboxes in particular can constitute a source of potential failure. Such inspection or service requires that the gearbox housing or casing be opened to allow access to the interior, with components such as shafts, gears and bearings within the gearbox being removed therefrom in order to allow full inspection.
Typically, such lifting is conducted with the use of a separate full height service crane alongside the wind turbine. In order to allow the crane access to the gearbox, the roof of the nacelle cover must be removed or opened. This operation utilising an external crane is extremely time consuming and expensive, and potentially dependent on calm weather conditions. Recent designs of wind turbine are commonly provided with internal nacelle cranes, either of a fixed type, or swivelable, or slidable on rails whereby the crane can be moved over the gearbox for assisting in a service operation. However, many older designs of turbines still in use today are not provided with such cranes.
It is proposed to provide a lifting tool which is able to be used for gearbox servicing and which can be brought up inside the turbine within the nacelle in order to lift components from within the gearbox, and without needing to remove or open the nacelle cover.